Water heating system



Dec. 1941- c. M. OSTERHELD WATER HEATING SYSTEM Filed Nov. 18, 1940 MEIENTOR S7 RHELD CLARK ATTORNEY Patented Dec. 16, 1941 WATER HEATING SYSTEM Clark M. Osterheld, Stoughton, Wis, assignor to McGraw Electric Company, Elgln, 111., a corporation of Delaware Application November 18, 1940, Serial No. 366,055

7 Claims.

My invention relates to water heating systems and particularly to off-peak electric water heatingsystems.

One of the objects of my invention is to provide a relatively simple system whereby an operator in an electric power station can selectively control the energization of fluid tank heaters connected to the system supplied with electricity from the power station.

Another object of my invention is to provide a relatively simple, power house-controlled means and system whereby the operator can be assured that each of the tanks contains at least a predetermined amount of hot fluid during the day and that all of the tanks have their heaters energized during the off-peak period to ensure starting the daylight hours with a substantially full tank of fluid.

Other objects of my invention will either be apparent from a description of a system embodying my invention and now preferred by me or will be pointed out in the course of such description and set forth in th appended claims.

In my copending application Serial No. 365,919, filed November 16, 1940, I have disclosed and claimed a tank water heating system embodying my invention as applied to an individual hot water tank and this application covers the use of a specific form of remote control for a plurality of such hot water or fluid-containing tanks distributed over the area supplied with electric current by the electric power station.

In the single sheet of drawings, I have illustrated a plurality of individual hot water or fluid-v containing tanks and the control elements associated with the individual tanks and water heaters, including a remotely controllable control means, in combination with an electric power station.

I have illustrated a plurality of hot water tanks I I, which may be of the ordinary elongated cylindrical type now so commonly used in domestic 'Other details such as are usually supplied with hot water tanks or fluid-containing tanks may be used but since these form no part of my invention I have deemed it unnecessary to illustrate and describe the same.

I provide'a lower main thermal switch I! here illustrated as including a tubular member 19 secured in a fluid-tight manner to the wall of the tank to be located inside of the tank. An expansion rod 2i is mounted in the tubular member and engages a resilient contact arm 23 which is normally yieldingly biased into engagement with a rigid contact arm 25 and is disengaged therefrom when the thermal switch I7 is responsive to the relatively high temperature of hot water or other fluid. I wish to point out here that while I have shown specific positions of the heater l3 and of the thermal switch 11, I do not desire to be limited exclusively thereto nor do I desire to be limited to the construction shown. Any other thermallyactuable heater control switch now available in the art may be used by me and is to operate to cause disengagement of the contact arms when substantially all of the water or fluid in the tank is hot.

I provide an upper auxiliary thermally actuable switch 21 which includes a tubular member 29, an expansion rod 31 adapted to engage and move a resilient contact arm 33 out of engagement with a rigid contact arm 35 which it normally engages as long as the temperature of the water surrounding the tubular member 29 is relatively low or the water or fluid is cold. It is to be understood that the auxiliary thermally actuable switch 21 is of substantially the same general design as the lower main thermally actuable switch I1. I provide a remotely energizable control element 3'1 in the form of an electromagnetic switch including a coil 39 having a magnetizable core member therein magnetically connected with a contact bridging member 41 which latter is adapted to engage with and be disengaged from a pair of fixed contact members 43-. I have illustrated this electromagnetic control member and heater control switch generally only since its design and operation are already well known in the art.

I provide also a second electromagnetic switch A supply circuit conductor 53 is connected tov one of the fixed contact members 43 and a conductor 55 connects conductor 53 and the fixed contact member 43 to one of the fixed contact members 5|. The other contact member 43 is electrically connected by a conductor 51 to the other fixed contact member 5i and to one terminal of the heater I3. The other terminal of I the heater I3 .is connected by a conductor 59 to contact arms 25 and 35. Contact am 23 is connected by a conductor 6! to the other supply circuit conductors 63. Contact arm 33 is connected toone terminal of coil 41 by a conductor 35 while the other terminal of coil 4? is electrically connected to that fixed contact member 5! which is connected by a conductor t'l to conductor 51.

I have illustrated an electric power station 99 by a rectangular figure and have further illustrated generally. only a suitable source of supply of alternating current electric energy by the usual symbol for an alternating current generator bearing the numeral II. Control means for the electric energy generated by the generator II or by any cooperative plurality thereof, driven by anysuitable power mean-s, is indicated by a knife blade switch I3 which is adapted to energize or deenergize, in any suitable or desired manner, a bus bar system including bus bars "I5 and ll. These bus bars are connected to distribution circuits indicated generally by the numerals I9 and BI and are to be understood as being of any size and of any length and may have any number of sub-distribution current conducting wires or members connected therewith to distribute the electric energy over a given area. I have illustrated the source of current for the individual supply circuit conductors 53 and 63 as including conductors 03 and 85, and have indicated the fact that there may be some distance between the bus bar system, the distribution circuits, and the individual installations by the broken lines extending from conductor 53 to conductor 83 and from the conductor, 63 to the conductor 35.

I provide awsuitable source of control means for the coil 39 ofv the respective and individual control elements 31 by providing a secondary current distribution system including a manually actuable switch 81 adapted to be electrically connected withbus bars I5 and II, by conductors 39 and 9H and adapted to energize an auxiliary set of bus bars or conductors 93' and 95 which are connected to a secondary distributioncircuit, shown generally only as including two conductors 91 and 99 which are also to be understood as extending over the area served by the power station. .One terminal of each of the coils 39 is connected by a conductor IN to a dis tribution circuit conductor I03 which is shown as being connected to conductor 99. The other terminal of coil 39 is connected by conductor I05 with conductor I'I' which, in turn, is shown as being connected to the conductor 9'I of the secondary distribution circuit. I have shown conductors IOI and I03 and conductors I and I01 out that any desired distance may be present between the supply circuit conductors I0! and hours, to ensure starting the daylight hours of a 75 twenty-four hour day. with substantially each tank full of hot water or fluid.

"It may be assumed, merely for illustrative purposes, that the operator in the power station 69 will cause momentary closing of the secondary control switch 31, which he may do manually or by any other suitable control means in accordance with the type of control switch provided. This will momentarily energize each coil 39 of the control element 37 of the respective tank heating systems. Let it be assumed further that this energization is effected several hours after the end of an off-peak period, say 10*.00 A. M., and that in a given tank selected merely for illustrative purposes, the auxiliary thermal switch 2? is surrounded by cold water, that is, that withdrawals of hot water from the tank have been enough as to remove such an amount of the original hot fluid content of 'the tank between the time of ending of the ofi-peak period and the time of first closure of the control switch 31 as to subject the auxiliary thermal switch 21 to the temperature of cold water. An energizing circuit is momentarily closed as follows: from supply circuit conductor 53 through engaged contact members A33 and 65, through conductor 51, through heater I3, through conductor 59, through engaged contact arms 25 and 23 and from there through conductor 3! to the other supply circuit conductor 63. It is, of course,'to be understood that sufiicient hot water has been withdrawn from the individual tank to subject the main thermal switch I! to the temperature of cold water and it is to be further noted that if no hot water had been withdrawn from the indiengaged contact arms 33 and 35, through conductor 59, through engaged contactarms 25 and 23 and from there through, conductor 6| to the other supply circuit conductor 93. This causes energization and upward movement of the core in coil 41 and therefore of the contact bridging member 49 which latter then engages fixed contact members 5! This closes an auxiliary circuit through the heater as follows: from supply circuit conductor 53 through conductor 55, through the engaged contact members 5| and 49, through conductors 01 and 51, through'heater I3, through conductor 59, through the engaged contact arms 25 and 23 and from there through conductor BI to conductor 63. A holding circuit is also established for coil 41 independently of the control element 3'! as follows: from supply circuit conductor 53 through conductor 55, through engaged contact members 5| and 49, through the coil 41, through conductor 55, through engaged contact arms 33 and 35, through conductor 59, through engaged contact arms 25 and 23 and from there through conductor 5| to the other supply circuit conductor 53. It is evident that this holding circuit is independent of the control element 31 and since, as hereinbefore stated, the coil 39 was energized momentarily only by the remotely located control means 81, opening of the electromagnetic control element will have no efiect upon the energization of the heater I3 through the circuit hereinbefore described which, energization predetermined amount of hot water.

terruption of the holding circuit through the coil 3'1 and therefore deenergization of the heater l3.

The operator in the central station may, there- .fore, either manually or by any other suitable means effect energization of the secondary distribution circuit controlling the remotely controllable means 31 in each of the heater systems connected to the distribution circuit to thereby pick out, if it may be so termed, those tanks which contain less than a predetermined amount of hot water and ensure that within a reasonable length of time, they will contain at least such For purposes of illustration I may mention that it may be desirable to have the control means 81 in the central station closed every two or every three hours during the day and it is evident that only those heaters will be continuously energized for a length of time varying with the amount of hot water in the tank, that is, the greater the amount of hot water already in the tank at the time of a momentary energization, the shorter will be the resultant continuous energization of the heater, which, as hereinbefore stated, will be interrupted by thermally controlled means closely associated with the tank.

It is further desired to ensure that all of the tanks having electric heaters connected to the system shall be full of hot water at about the end of an off-peak period which, for purposes of illustration, may be considered to end at 6:00

A. M. In order to ensure this continuous operation of all of the heaters connected to the system individually associated with hot water tanks, where all of the water in the tank is not hot. the operator merely closes the control switch 8'! at some preselected time such as 1:00 A. M. or 2:00 A. M. and leaves it in closed position until say a short time before the end of the oil-peak period which, as stated hereinbefore, may be considered to end at or about 6:00 A. M. As is Well known, the extreme dip or valley in the load curve on the central station occurs during the late night and 'a continuous energization of all those heaters associated with tanks not completely full of hot Water from say 1:00 A. M. or 2:00 A. M. to just before 6:00 A. M., will ensure that at the end of an oif-peak period when the total load on the station begins to rise sharply, all or substantially all of the tanks having heaters connected to the supply system will have their fluid contents in a heated condition. It is to be understood, of course, that the main thermal switch I? in each of the individual installations will cause interruption of the energization of the heater i3 and of the holding circuit of the coil 41 as soon as all or substantially all of the fluid in the tank is hot.

My invention thus provides a relatively simple means for power house control or for remote control of a plurality of electric heaters applied to hot water or fluid tanks whereby relatively simple control means in the power house closed momentarily at spaced times during a part of theday and closed continuously during another part of the day, namely the off-peak period, will ensure the start of the daylight period with tanks full or substantially full of hot water or fluid and will maintain at least a predetermined fractional part of the fluid content of each tank hot during the daylight hours and during the early evening hours as well.

I have shown the usual domestic hot water tank in the drawing but have used the term fluid to indicate that my heating system may be used for fluids other than water. Thus it is possible to use my improved heating system on tanks containing, for example, fuel oil which it is desired to heat before being used, or for heating any other fluid where it is desired to start off at some predetermined time when low power rates become eifective or are eifective to heat all of the tank content during the off-peak period and then to maintain in a heated condition a predetermined fractional part of the tank content.

I desire it further to be understood that I may use any of the other control systems mentioned in the copending application Serial No. 365,919, filed November 16, 1940, instead of the particular one illustrated in the drawing and described in the specification.

Various modifications may be made in the system embodying my invention without departing from the spirit and scope thereof and I therefore desire that all such modifications as are clearly covered by the appended claims shall be included as a part of my invention.

I claim as my invention:

1. An electric current distribution system energized by an electric power station and comprising a plurality of distributedelectric water tanks each having an electric heater near the lower end of the tank adapted to be energized from said system,'hea ter-circuit control means for the individual electric heaters each including a main and an auxiliary electromagnetic switch, electric circuit connections between the power station and the individual heater-circuit control means and manually-actuable means in the power station for optionally energizing said main electromagnetic switches momentarily to effect energization through the auxiliary electromagnetic switch of those heaters associated with tanks in which less than a predetermined fractional part of the water content is hot and continuously to efiect energization through the main electromagnetic switch of all heaters associated with tanks in which less than all of the Water content is hot.

2. An electric current distribution system adapted to be energized by an electric power station and comprising a plurality of distributed electric water tank heaters adapted to be energized from said system, heater-circuit control means for the respective electric heaters each including a main and an auxiliary electromagnetic switch, a main and an auxiliary thermally actuable switch responsive to tank water temperature at different points in the tank, electric circuit connections between the electromagnetic and thermally actuable switch of each heater and between the main electromagnetic switches of all heaters and the power station and manually-operable means in the power station for effecting energization of all of the main electromagnetic switches momentarily at selectively spaced intervals of a day to cause energization of the heaters of those tanks in Which less than a predetermined fractional part of the water content is hot until said predetermined fractional part of the water content is hot.

3. An electric current distribution system adapted to be energized by an electric power station and comprising a plurality of distributed electric water tank heaters adapted to be energized from said system, heater-circuit control means for the respective electric heaters each inmagnetic switches momentarily at selectively spaced intervals of a day to energize the heaters of those tanks in which less than a predetermined fractional part ofthe water content is hot until said predetermined fractional part of the water content is hot and continuously over a predetermined length of time to energize the heaters of all of the tanks in which less than the full water content is hot.

4. An electric current distribution system adapted to be energized by an electric power station and comprising a plurality of distributed electric water tank heaters adapted to be energized from said system, heater-circuit control means for the respective electric heaters each including a main and an auxiliary electromagnetic switch, amain and an auxiliary thermally actuable switch responsive to tank water temperature at diiferent points in the tank, electric circuit connections between the electromagnetic and thermally actuable switches of each heater and between the main electromagnetic switches of all heaters and the power station and manually-operable means inthe power station for effecting energization of all of the main electromagnetic switches momentarily at selectively spaced intervals of a day to cause energization of the heaters of those tanks in which less than a predetermined fractional part of the water content is hot, the respective auxiliary thermally actuable switches causing deenergization of their electric heaters when said predetermined fractional part of the water is hot.

5. An electric current distribution system adapted to be energized by an electric power station'and comprising a plurality of distributed electric water tank heaters adapted to be energized from said system, heater-circuit control means for the respective electric heaters each including a main and an auxiliary electromagnetic switch, a main and an auxiliary thermally actuable switch responsive to tankwater temperature at different points in the tank, electric circuit connections between the electromagnetic and thermally actuable switches of each heater and between the main electromagnetic switches of all heaters and the power station and means in the power station for optionally efiecting energization of all of the main electromagnetic switches momentarily at selectively spaced intervals of a day to energize the heaters of those tanks in which less than a predetermined fractional part of the water content is hot until said predetermined fractional part of the water content is hot and continuously over a predetermined length of time to energize the heaters of all of the tanks in which less than the full water content is hot, thermal deenergization of the electric heaters energized by momentary energization of all of the main electromagnetic switches connected to the system being effected by the auxiliary thermally actuable switches connected with the energized heaters when said predetermined fractional part of the water content of any tank is hot and thermal deenergization of electric heaters energized by continuous energization .of the main electromagnetic switch being effected by the main thermally actuable switches connected with the energized electric heaters when substantially all of the water content is hot.

6. An electric current distribution system adapted to be energized by an electric power staa tionand comprising a plurality of distributed electric water tank heaters adapted to be energized from said system, heater-circuit control means for each of the respective electric heaters including an electromagnetic switch having a coil, an electric circuit from said coil to the power station and manually-actuable means in the power station to selectively energize the coil circuit momentarily and continuously, momentary energization of the coil circuit effecting energization of the heaters on tanks in which less than a predetermined fractional part of the water content is hot and continuing energization of the coil circuit, effecting energization of the heaters on tanks in which less than the full water content is hot.

7. An, electric current distribution system adapted. to be energized by an electric power station, a plurality 'of distributed hot water tanks, each having a single electric heater at the lower end of the tank and current-distribution circuits connecting the electric heaters and the electric power station, heater-circuit control means for the respective heaters including a main and an auxiliary electromagnetic heater control switch, a main and an auxiliary thermal heater control switch located at difierent heights of the tank, electric connections between the heater and the switches for each tank and manually operable means at the power station for selectively energizing the coil of the main electromagnetic switch of each heater momentarily and continuously at different times of a day, momentary energization of the coil of the main electromagnetic switch of each heater causing energization through the auxiliary electromagnetic switch and the'auxiliary thermal switch of the heaters of those tanks in which the auxiliary thermal switchv is subject to cold water and continuous energization ofv the coil of the main electromagnetic switch of each heater causing energization through the main electromagnetic, switch and the main thermal switch of the heaters of those tanks in which the main thermal switch is subject to cold water.

- CLARK M. OSTERHELD. 

